Many palm-top personal computers and Personal Digital Assistants (PDA) use a small pen or stylus that works in conjunction with the palm-top personal computer or PDA screen. A user inputs data by pressing the stylus or pen against the screen. The processor contained in the palm-top personal computer or PDA responds to stylus or pen movement as an input signal and processes any input data to recreate handwritten signatures and communications, open menus, or input other data.
In an advance over some of the Personal Digital Assistants and palm-top computers, Published International Application PCT/GB98/03016 discloses a portable computer that is configured to be hand held, functions as a pen, and includes a small display screen. Accelerometers are positioned near the writing tip at the base of the hand-held computer pen and detect movement of the computer as a pen with respect to gravity to provide input into a microcontroller and select from a number of viewing modes a proper response. Personal Digital Assistant and palm-top computer functionalities are incorporated into the large plastics casing that acts as a pen, including the functions of a calendar, contacts, scrolling, voice, e-mail, diary, data entry, calculator, and other functions, as is typical with many commercially available Personal Digital Assistants. An accelerator detector is incorporated into this portable computer pen and detects x and y movement components at a 90° angle. This hand-held computer pen can include a sound input device for recording voice messages. An infrared transceiver can be mounted at the front of the casing to allow any data that has been processed to be transferred to a lap-top or other computer for storage or subsequent processing.
In this sophisticated hand-held computer pen, the microcontroller or processor contained in this device uses the output from the accelerometers to determine what different views should be displayed on the screen. This creates a virtual hinge. When a user moves the stylus while it is in the viewing position, the screen information can be changed to respond to any natural reaction, such as for looking up or down or to the left or right. For example, if the screen is designated a current page, then if the stylus or pen is tilted toward the left, the accelerometers would determine the change in position and cause the display of the page to move to the right of the current page.
It is possible also that through a process of auto-correlation from the processor within the pen, data received from the accelerometers can determine what characters had been entered. With sophisticated programming contained within the hand-held computer pen, some cursor movement and passwords and signatures can be processed.
Although the hand-held computer pen as described provides functionality for character analysis, all functions are contained within a large, hand-held unit, which is cumbersome. It would be more advantageous if a standard pen could have some functionality for determining movement of its writing tip without the necessity of having on-board processing capability that would demand volume space as in the invention described above. It would be even more advantageous if an ink cartridge alone could have such functionality, allowing it to be inserted within many different types of pen bodies.